In a gas turbine engine used to power an aircraft, malfunctions sometimes occur. While many malfunctions are minor, some are significant enough to reduce thrust of the engine to a large degree. For example, if the engine ingests a large bird, damage can occur which significantly compromises the thrust-producing ability of the engine. As another example, a missile fired by a terrorist can produce similar damage, or worse. As a third example, during take-off, the engine can ingest debris left on a runway.
In such cases, the pilot can take at least two strategies. One is to continue operation of the engine, but at the reduced thrust level. The second is to shut down the engine. The invention provides another strategy for operating a malfunctioning gas turbine engine.